Ships hulls and other surfaces kept in ocean waters are continually fouled by marine organisms such as barnacles, algae, and mussels. Fouling means that marine organisms attach to ship hulls. Fouling increases drag, reduces ship speed, and greatly increases fuel usage, along with environmental pollution.
Estimates of the impact of fouling are difficult to obtain. However there are some broad examples. In 1990 the United States Navy estimated that fouling increased fuel consumption by $500 million per year. The commercial shipping industry runs far more ships than the United States Navy and, consequently, uses much more fuel and incurs much more cost. The market potential for an improved antifouling coating could easily reach into the billions of dollars per year.
Current antifouling paints are painted on ship hulls and other surfaces kept in ocean waters. Current antifouling paints are used to reduce fouling by marine organisms. Current antifouling paints rely on release of metals, such as copper or sometimes tin, into the surrounding water. These metals act as general biocides and kill marine organisms. Metal pollution has had unintended consequences, such as the ability to kill all marine life beyond the ship hull such as within the surrounding water.
From an environmental perspective, this approach is not optimal. Tin coatings have been banned and legislation has passed to ban the use of copper-based coatings. However, no large scale alternative has been found. The phasing out of biocidal copper coatings may have been delayed until an alternative, non-toxic coating can be developed.